Drilling bit



Patented Feb. 22, 1944 UNITED STATES PATENT OFFICE j] DRILLING BIT Ferdinand J. Spang, Butler, Pa.

- Application January 24, 1942, Serial No. 428,065

4 Claims.

' This invention relates to bits for use in well drilling, and more particularly to bits for use in cable tool system 'of drilling.

In drilling wells through an inclined or'sloping formation, it is rather diificult to keep the drilling bit from following, transverse fissures which were caused as the formation was lifted from horizontal position during the formative period.

This tendency of the drilling bit to follow these fissures frequently leads well bores to such an inclination (angle to the vertical) that it becomes necessary to refill the bore for a portion of its depth and then attempt to drill away from the inclined or angled portion.

Many methods of straightening crooked or inclined well bores, in formations having transverse fissures, have been tried but such methods, so far as I amaware, have met with but slight, if any, success.

One object of this invention is to produce a drilling bit for use in the cable tool system of drilling and by means of which a sloping or crooked well bore can be straightened without refilling a portion of the bore hole. I

Another object is to produce a drilling bit for use in the cable tool system of drilling andby means of which tendency of the bit to follow a transverse fissure in a sloping formation is mini-'- mized.

Another object is to produce a'clrilling bit for use in cable tool drilling, and which, when used in a formation having transverse fissures which have a tendency to cause the bore to veer'from the vertical, digsthe lowerside of the bore hole ahead of the upper side, and thus tends to straighten the hole or bring it back to the vertical.

These and other objects whichwill be apparent to those skilled in this particular art, I attain by means of the drilling bitsdescribed in the specification and illustrated in the drawing accompanying and forming a part of this application.

In the drawing:

Figure 1 is a more or less diagrammatic view and illustrates a bit 'of this invention attached to a drilling string. The bit is shown within a sloping or angled bore hole located within a sloping formation having transverse fissures;

Fig. 2 is a view similar to Fig. 1, but in this view, the bit is shown in a straight portion of the bore hole;

Fig. 3 is a perspective view of the bit of this invention looking toward its light side; and

Fig. 4 is an enlarged'transverse sectional view taken at some point intermediate the ends of the bit blade and looking toward its'upper end.

In a general way, but only in a general way, the bit of this invention follows the design of standard paddle type bits such "as used 'in drilling wells by the cable tool system of drilling. The bit of this invention differs from'standard paddle type bits in certain essential particulars and it is by these that I attain the objects of this invention.

In the bit of this invention, the blade on one side of its longitudinal center "is much heavier than on its opposite side. 1 The water course within the blade is located off its longitudinalcenter and toward its lighter'side. the bit is attached to the'drilling stem is located on the heavier side of the blade, 1 and is preferably so positioned that a portion ofits outer peripheral surface is in alignment 'with'fthe outer peripheral surface of the heavy side of the blade. The cutting edge (the point of the bit which does the drilling) is formed at a slight angle, or in other words, is formed at an angle to a line which is perpendicular to the longitudinal center line of the blade, instead of being perpendicular to the longitudinalcenter lineas in standard type paddle bits.

In the bit chosen for illustration of this invention, side 5 of the blade is much heavier than its opposite side 6. The water course I within each side of the blade is locatedoff the longitudinal center line or axis of the. blade and, is nearer light side 6 than heavy side 5. Pin 8 which is threaded at 9 for attachment to the drilling stem, is so located that it is in line with the heavy side 5 of the blade. The cutting edge I0,- orthatpart of the bit which does the cutting, isformed at a slight angle to the normal or standard cutting edge. In other words, as before pointed out, outting edge l0 stands at a slight angle to a line which is perpendicular to thelongitudinal axis of the blade, and this cutting edge extends laterally outward beyond edge H, which edge is the outer edge of the heavy side 5. This forms a cutting point [2. g

In cabletool drilling, the bit is attached to a stem or sinker bar' above which is a set of jars,

and a socket by which the unit is attached to the drilling cable by means of which reciprocatory motion for drilling is produced.

During this reciprocatory motion, the drilling string has a tendency to rotate, due to the rotative force occasioned by the winding and unwinding of the cable which is alternately in stress The pin by which and out of stress. While this rotative force is of but limited magnitude, it is still suflicient, when the bore hole has reached a considerable depth, and the drilling tools are in balance, (as they are when a standard paddle type drilling bit is used) to cause sufficient rotary motion to enable the bit to operate without the use of any other swiveling mechanism.

This rotative force will turn the bit to enough chance positions to drill a fairly accurate round hole in formations that lie relatively flat or that are relatively free from angular or transverse fissures. However, where angular or transverse fissures are present, or where an interlaid structure is present, the tools have a tendency to rotate less freely with the result that the drilling bit is apt to follow such interlaid structure or such transverse fissures.

The bit of this invention, when attached in the usual manner to a drilling cable through a A stem or sinker bar, a set of jars and a socket, tends to arrest the swiveling action due to its lack of balance. This causes the heavier side of the bit to slide up and down the lower side of a sloping or inclined bore hole.

By forming the cutting edge ID of the bit at a slight angle to a line which is perpendicular to the longitudinal axis of the bit, and extending the cutting edge to form point 12 which extends slightly beyond the outer Wall of the bit body on the heavy side, cutting point l2 digs ahead on the lower side of the sloping or angled bore hole, as indicated at 13 in Fig. 1. Because of this action, the bit of this invention straightens the bore hole to a vertical condition.

As soon as the bore hole has been straightened, the lack of balance in the bit is relatively unimportant and the tools will again swivel into a full group of chance positions, so that the bore hole, as it progresses will be relatively round.

However, because of the fact that the cutting edge of the bit is slightly angled to a normal cutting edge, the tendency of this bit is to drill a slightly oversized hole. This, however, is of no importance.

Lessening of the swiveling or rotary motion of the drilling tools, due to lack of balance of this bit, is not enough to prevent sufiicient swiveling to allow the cutting edge to reach enough chance positions to keep the bore hole relatively round as it is being changed from a sloping or angled position to a straight or vertical position.

The bit of this invention is not designed to straighten a bore hole that has been completed, but rather to draw back to vertical position part of that portion which has become sloping or angled so that the continuing portion therebeneath will be vertical. It will be noted that so long as the bore hole is sloping or angled, the heavier side of the bit will ride the inclined lower surface with but slight rotary oscillation. However, when the bore hole has reached a vertical condition, this oscillation will increase until the cutting edge of the bit contacts with all of the inner periphery of the bore hole, as drilling proeresses.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A cable tool paddle type bit for use in drawme back to vertical the lower face of an inclined portion of a Well bore hole; said bit having one side of its blade materiall heavier than it opposite side; said bit having a water course off the longitudinal center of the bit toward its lighter sid and having a pin for attachment to a drilling stem and which is located oif said longitudinal center toward its heavier side; the cutting edge of the bit being formed at such an angle to a line which is perpendicular to the longitudinal center of the bit, that during operation in such inclined portion of the bore hole, the cutting point on the heavier side of the bit is in advance of the cutting edge on the lighter side thereof.

2. A cable tool drilling bit for use in drawing from an inclined to a vertical condition the continuing portion of a well bore hole, said bit body having two longitudinally extending sections of relatively different weights with water courses formed in the portion connecting such sections and with the member for connecting the bit to the drilling stem being in approximate alignment with the heavier of such sections; the construction and arrangement being such that the ofi center position of such member and the excess Weight of the heavier section cause the heavier section to gravitate to a position such that the cutting edge located on its lower end will drill more eifectively on the lower side of the inclined portion of the bore hole than on the upper side thereof.

3. A cable tool drilling bit for use in drawing back to the vertical the lower side of the inclined portion of a well bore hole; said bit comprising a body having two longitudinally extendin sections of materially difierent weights, with the member for connecting the bit to a drilling stem in approximate alignment with the heavier section; said sections being so formed as to provide longitudinally extending water courses on opposite sides of the bit; the lower ends of said sections being formed as a cutting edge; the construction and arrangement being such that the weight of the heavier section of the bit causes the sam to gravitate to a position such that the cutting edge thereof will drill more effectively on the lower face of the inclined portion of the bore hole than on the upper face thereof.

4. A paddle type cable tool drillin bit for use in drawing back to vertical the continuing portion of a well bore hole in which a portion of the bore hole above such continuing portion has become inclined; said bit on one side of its longitudinal center being enough heavier than on its opposite side as to cause the heavier side during drilling in such inclined portion of the bore hole to gravitate to the lower side of such inclined portion; the cutting edge of the bit being so formed and arranged that the portion thereof on the heavier side lies in advance of that on the lighter side during operation in such inclined portion of the bore hole; the member by means of Which the bit is connected to a drilling stem being in substantial. alignment with the heavier side of the bit.

FERDINAND J. SPANG. 

